Wet-Bulb Temperature Estimator mechanism

Model scope

NEEDS_REVIEW because the instrument does not define which of the two claimed algorithms is authoritative. For a deterministic plain-arithmetic implementation, explicitly select Stull (2011), document that pressure is ignored, validate T and RH, and label the output as an empirical approximation. Alternatively, specify the complete pressure-dependent iterative psychrometric model and convergence tolerance.

• The specification names two materially different algorithms—Stull (2011) and an iterative psychrometric energy balance—but does not select one or define the iterative equations, psychrometric constants, saturation-vapor-pressure correlation, or convergence criterion.
• The Stull formula does not use barometric pressure, so the declared P input is ignored when that method is selected. Pressure is required for a pressure-aware psychrometric calculation.
• The Stull correlation is an empirical approximation, not a general psychrometric energy-balance solution; its stated approximate validity range and error should be displayed honestly.

Units and conventions

• Stull inputs are dry-bulb temperature T in degrees Celsius and relative humidity RH in percent from 0 to 100, not a fraction from 0 to 1.
• The Stull formula uses inverse trigonometric functions in radians.
• Barometric pressure P is not used by the Stull formula. If P is intended to affect the result, its units and the complete pressure-corrected algorithm must be specified.
• Outputs are degrees Celsius when T is supplied in degrees Celsius.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "method": "Stull 2011",
    "dry_bulb_C": 20,
    "RH_percent": 50,
    "pressure_kPa": 101.325
  },
  "expected_outputs": {
    "wet_bulb_C": 13.699
  },
  "working": "Use Tw = T*atan(0.151977*sqrt(RH+8.313659)) + atan(T+RH) - atan(RH-1.676331) + 0.00391838*RH^(3/2)*atan(0.023101*RH) - 4.686035. sqrt(50+8.313659)=sqrt(58.313659)=7.63634. First angle: atan(0.151977*7.63634)=atan(1.16055)=0.859571, so T term=20*0.859571=17.1914. atan(20+50)=atan(70)=1.556512. atan(50-1.676331)=atan(48.323669)=1.550105. RH term: 50^(3/2)=353.553; 0.00391838*353.553=1.38536; atan(0.023101*50)=atan(1.15505)=0.857222; product=1.18756. Therefore Tw=17.1914+1.556512-1.550105+1.18756-4.686035=13.6993 C, or 13.699 C. P is unused."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A negative-RH input drives the RH^(3/2) term outside the real-number domain and can yield NaN unless rejected. The specification also leaves the Stull-versus-iterative method and the validity-limit branch unspecified, while RH unit convention can be interpreted as either percent or fraction.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche6/tranche6-results.json
• BOUNDARY_HAZARD_CATALOG.json